WebSocket API Reference

Event-driven connectivity for payments and trading.

Paxos provides secure, real-time market and execution data feeds via public WebSocket connections The Stablecoin Market Price Feed streams event-driven updates for the market index price for external stablecoins. The Market Data Feed streams event-driven updates for the entire order book or for a single market. The Execution Data Feed streams event information for all markets or for a single market.

See the Websocket trading and stablecoin payments guides for a hands-on introduction.

The WebSocket connections provide a number of advantages when compared to the v2 API, including real-time event notifications, minimized data transfers over the network and reduced latency when compared to a polling strategy.

Connection Details

Once a secure (wss://) connection is established, each feed begins streaming data, subject to the rate limits. Both Production and Sandbox data feeds have a built-in, instantaneous failover. Clients should have a reconnection mechanism in case of server disconnection.

Sandbox Data Feeds

wss://ws.sandbox.paxos.com/executiondata
wss://ws.sandbox.paxos.com/executiondata/{market}
wss://ws.sandbox.paxos.com/marketdata
wss://ws.sandbox.paxos.com/marketdata/{market}
wss://ws.sandbox.paxos.com/marketdata/stablecoin/{market}

Production Data Feeds

wss://ws.paxos.com/executiondata
wss://ws.paxos.com/executiondata/{market}
wss://ws.paxos.com/marketdata
wss://ws.paxos.com/marketdata/{market}
wss://ws.paxos.com/marketdata/stablecoin/{market}

Execution Data Feed

Upon secure (wss://) connection, you will start to receive messages for each market execution (based on the use of the market parameter). The first message corresponds to the last execution for the market at the point of the connection. After that, each new message represents a new execution.

If there are no executions for longer periods of time for a particular market upon connection you may not receive any message until a new execution is made.

Upon reconnection you will receive the last execution for the market, in which case clients should handle duplicate messages. You may use a match number as an idempotent field.

Execution Data Request

Sandbox: wss://ws.sandbox.paxos.com/executiondata
Production: wss://ws.paxos.com/executiondata

Execution Data Path Parameter

Sandbox: wss://ws.sandbox.paxos.com/executiondata/{market}
Production: wss://ws.paxos.com/executiondata/{market}

Parameter	Required	Description
`market`	No	Filter the data stream for a single market. For example, `BTCUSD` or another market from available markets.

Execution Data Response

Parameter	Required	Description
`market`	Yes	One of the available markets or the single market if the `market` path parameter is specified.
`price`	Yes	The execution price.
`amount`	Yes	The execution amount.
`executed_at`	Yes	Timestamp of the execution.
`match_number`	Yes	Unique execution number.

Execution Data Example Response

Request URL: wss://ws.sandbox.paxos.com/executiondata/BTCUSD

{
  "market": "BTCUSD",
  "price": "24228.75",
  "amount": "0.00000412",
  "executed_at": "2023-03-13T18:46:53.386Z",
  "match_number": "6AJVAX7BTCH8"
}
...

Market Data Feed

Once a secure (wss://) connection is established, the initial response message shows the state of the order book, including both bids and asks, in the SNAPSHOT. Prices are in descending order for bids and ascending order for asks.

When streaming data for all markets, differentiate the per-market updates using the market field.

Available Markets

The public feeds may contain inactive markets or markets unavailable for trading. Availability varies depending on the environment. For example, we may enable a market in the Sandbox environment for testing but not in Production. Some Paxos accounts have additional trading restrictions in Production.

Get Order Book retrieves a list of markets available for trading and List Recent Executions retrieve a list of all platform trades. However, these endpoints are not suitable for streaming order book and execution event data.

Market Data Request

Sandbox: wss://ws.sandbox.paxos.com/marketdata
Production: wss://ws.paxos.com/marketdata

Market Data Path Parameter

Sandbox: wss://ws.sandbox.paxos.com/marketdata/{market}
Production: wss://ws.paxos.com/marketdata/{market}

Parameter	Required	Description
`market`	No	Filter the data stream for a single market. For example, `BTCUSD` or another market from available markets.

Market Data Initial Response

Parameter	Required	Description
`type`	Yes	The initial value of `SNAPSHOT` shows the state of the order book for both `bids` and `asks`. Subsequent messages show all executed trades, and other order book changes, in the `UPDATE` stream.
`market`	Yes	One of the available markets or a single market if the `market` path parameter is specified.
`bids`	Yes	Includes `bids.price` in descending order and `bids.amount`. Each `price`-`amount` pair represents a level of the book.
`asks`	Yes	Includes `asks.price` in ascending order and `asks.amount`. Each `price`-`amount` pair represents a level of the book.
`final_snapshot`	Yes	Demarcates the end of the initial `SNAPSHOT`. Initial value always `true`. Subsequent messages in `UPDATE` format.

Market Data Update Response

When processing UPDATE messages observe the following rules:

If side=BUY and amount=0, remove the existing entry with price price from the bids list.
If side=BUY and an entry with price price already exists in the bids list, update the amount for the given entry in the bids list to amount.
If side=BUY and no entry with price price exists in the bids list, add an entry with price price and amount amount to bids list.
If side=SELL, apply the logic used as for BUY to the asks list.

Parameter	Required	Description
`type`	Yes	Value always `UPDATE`. Show all executed trades, and other order book changes, in the data stream.
`market`	Yes	One of the available markets or the single market if the `market` path parameter is specified.
`side`	Yes	Value either `BUY` or `SELL`. Specifies the activity type.
`price`	Yes	The current price.
`amount`	Yes	The current amount.

Market Data Example Response

Request URL: wss://ws.sandbox.paxos.com/marketdata/BTCUSD

{
  "type": "SNAPSHOT",
  "market": "BTCUSD",
  "bids": [
    {
      "price": "19994.25",
      "amount": "0.7755"
    },
    {
      "price": "19993.75",
      "amount": "0.83676985"
    },
    ...
  ],
  "asks": [
    {
      "price": "19994.5",
      "amount": "0.97548541"
    },
    {
      "price": "19996",
      "amount": "1.135"
    },
    ...
  ],
  "final_snapshot": true
}

{
  "type": "UPDATE",
  "market": "BTCUSD",
  "side": "BUY",
  "price": "19958.5",
  "amount": "0.62649999"
}

{
  "type": "UPDATE",
  "market": "BTCUSD",
  "side": "SELL",
  "price": "20115.25",
  "amount": "0"
}
...

Stablecoin Market Price Feed

Once a secure (wss://) connection is established, the initial response message shows the market price. The feed currently supports the USDCUSD market.

Stablecoin Market Request

Sandbox: wss://ws.sandbox.paxos.com/marketdata/stablecoin
Production: wss://ws.paxos.com/marketdata/stablecoin

Stablecoin Market Path Parameter

Sandbox: wss://ws.sandbox.paxos.com/marketdata/stablecoin/{market}
Production: wss://ws.paxos.com/marketdata/stablecoin/{market}

Stablecoin Market Response

Price updates are pushed as they occur. The update frequency will typically be around 1 message per second, but may depend on market price volatility.

Parameter	Required	Description
`market`	Yes	One of the available markets or the single market if the market path parameter is specified.
`price`	Yes	The current price to 4 decimals.
`timestamp`	Yes	The time that the update occurred.

Stablecoin Market Example Response

Request URL: wss://ws.sandbox.paxos.com/marketdata/stablecoin/USDCUSD

{"market":"USDCUSD","price":"1.0001","timestamp":"2024-11-04T18:11:09.042391267Z"}

{"market":"USDCUSD","price":"1.0001","timestamp":"2024-11-04T18:11:10.049787567Z"}

{"market":"USDCUSD","price":"1.0001","timestamp":"2024-11-04T18:11:11.042710464Z"}

...

Connection Details​

Sandbox Data Feeds​

Production Data Feeds​

Execution Data Feed​

Execution Data Request​

Execution Data Path Parameter​

Execution Data Response​

Execution Data Example Response​

Market Data Feed​

Available Markets​

Market Data Request​

Market Data Path Parameter​

Market Data Initial Response​

Market Data Update Response​

Market Data Example Response​

Stablecoin Market Price Feed​

Stablecoin Market Request​

Stablecoin Market Path Parameter​

Stablecoin Market Response​

Stablecoin Market Example Response​